Tetrafluoroethylene (TFE) fine powder resins are non-melt-fabricable and are commonly processed by paste extrusion wherein the powder is mixed with a lubricant and is then discharged through a paste extruder to obtain films, tubes, tapes, protective coating on wire and the like.
Such paste extruded films, tubes and tapes can be rapidly stretched in unsintered form to form a strong material that is porous to water vapor but not to liquid water. Such a material is useful in providing "breathable" fabric material for garments, tenting, separatory membranes and the like.
It is desirable to prepare improved TFE fine powder resins having good stretchability in unsintered form after paste extrusion to obtain the strong breathable material described above. This invention is directed to the preparation of such resins by a process that produces resin at high reaction rates.